Brassinosteroids (BRs) are a group of plant steroid hormones with multiple roles in plant growth, development, and responses to stresses. In plants, BR deficiencies impair vital physiological processes and cause phenotypic abnormalities. A large number of studies show that BRs can positively influence plant responses to abiotic stresses such as heat, cold, drought, salinity, pesticides, and heavy metals. However, the underlying mechanisms of BR-induced stress tolerance are largely unclear. BR perception takes place in the cell surface by BR receptors, leading to a cascade of phosphorylation events to activate the central transcription factor BRASSINAZOLE-RESISTANT1 (BZR1) that controls the transcription of BR-responsive genes in the nucleus. BRs improve photosynthetic efficiency under stress conditions, which largely contributes to increased growth and biomass accumulation. Studies relating to exogenous BRs reveal a high dependency on concentrations with regards to BR effects on plants. Genetic studies show a positive correlation between the endogenous BR levels and abiotic stress tolerance, although this assumption contradicts with the performance of some BR mutants under stress conditions. Notably, plant responses to BRs greatly vary depending on the plant species, developmental stages, and environmental conditions. In addition, other hormones and signaling molecules that participate in fine-tuning the BRs effects also play an important role in plant adaptation to stress. Here, we review the involvement of BRs in plant responses to abiotic stresses. We also discuss available literature to show potential mechanisms of BR-induced abiotic stress tolerance. These studies signify the complexity of BR action in mediating stress responses in plants.

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植物对非生物胁迫耐受的油菜素类固醇

油菜素类固醇 (BRs) 是一组植物类固醇激素，在植物生长、发育和对胁迫的反应中具有多种作用。在植物中，BR 缺陷会损害重要的生理过程并导致表型异常。大量研究表明，BRs 可以积极影响植物对非生物胁迫的反应，如热、冷、干旱、盐分、杀虫剂和重金属。然而，BR 诱导胁迫耐受的潜在机制在很大程度上尚不清楚。BR 感知通过 BR 受体在细胞表面发生，导致一连串磷酸化事件以激活中心转录因子 BRASSINAZOLE-RESISTANT1 (BZR1)，后者控制细胞核中 BR 响应基因的转录。BRs 提高胁迫条件下的光合效率，这在很大程度上有助于增加生长和生物量积累。与外源 BR 相关的研究表明，BR 对植物的影响高度依赖于浓度。遗传研究表明内源性 BR 水平与非生物胁迫耐受性之间呈正相关，尽管这一假设与某些 BR 突变体在胁迫条件下的表现相矛盾。值得注意的是，植物对 BR 的反应因植物种类、发育阶段和环境条件而异。此外，参与微调 BR 效应的其他激素和信号分子也在植物适应胁迫中发挥重要作用。在这里，我们回顾了 BR 在植物对非生物胁迫响应中的参与。我们还讨论了现有文献，以展示 BR 诱导的非生物胁迫耐受性的潜在机制。这些研究表明 BR 在介导植物胁迫反应中的复杂性。